Emphysema

Emphysema is a long-term (chronic), irreversible lung disease that
occurs when the tiny air sacs in the lungs are damaged, usually as a result of
long-term smoking. It causes difficulty breathing and shortness of breath that
gets worse over time.

Emphysema is a form of chronic obstructive pulmonary disease
(COPD).

A rare type of emphysema is caused by the lack of a substance in
the lungs called alpha1-antitrypsin. This type of emphysema is usually
inherited.